Q 1(b). शीय वलन क्या होते हैं? इनकी उत्पत्ति की विरूपण अवस्था की विवेचना कीजिये । (UPSC 2025,10 Marks,150 Words)

Theme: Sheath Folds: Formation and Deformational Conditions Where in Syllabus: (Geology)
What are sheath folds? Discuss the deformational conditions of their formation.